Effect of surface oxidation on the magnetization reversal of cobalt planar wires

The influence of the antiferromagnetic layer of cobalt oxide on the magnetization reversal of a submicron cobalt planar wire was studied using the magneto-transport measurements. For pure Cobalt (Co) planar wires of width less than 1.2 μm, length of 30 μm, and thickness of 30 nm, the shape anisotropy dominates the magnetic behavior revealing all characteristics of a single domain structure. With oxidation, there is a thin layer of CoO on top of the Co layer and the exchange coupling between the CoO (antiferromagnet) and Co (ferromagnetic) layers may suppress the shape anisotropy induced single domain structure and the typical switching behavior of magnetization reversal. The magnetic configuration and magnetization reversal are determined by the competition of unidirectional anisotropy and exchange coupling constant.